Temperature control apparatus for frequency control devices



June 14, 1932. A. GEBHARD 1,352,929

TEMPERATURE CONTRQL APPARATUS FOR FREQUENCY CONTROL DEVICES I Filed March 16. 1929 s Sheets-Sheet 1 w I i go &? g ywwfi f i A TTORNEY June 14, 1932. GEBHARD TEMPERATURE CONTROL APPARATUS FOR FREQUENCY CONTROL DEVICES 3 Sheets-Sheet 2' &

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TEMPERATURE CONTROL APPARATUS FOR FREQUENCY CONTROL DEVICES Filed March 16, 1929 3 Sheets-Sheet 3 Y INVETVTOR. 04410 8. QeEfia a), BY .&s\

ATTORNEY 2 plicity tioned in a separate readily removable holder Patented June 14, 1932 UNITEDSTATES PATENT OFFICE LOU IS A. GEBHABD, OF WASHINGTON,-

DISTRICT OF COLUIBIA, ASSIGNOB RADIO, INQ, OF NEW YORK, N. Y.,

1-6. m m) A. CORPORATION OF DELAWARE TmEBATUBE CONTROL APPARATUS FOR FREQUENCY CONTROL DEVICES Application filed larch 16, 1929. Serial No. 847,554.

My invention relates broadly to electrical oscillation generators and more'particularly to housings for electromechanical vibrator elements.

5 One of the objects of my invention is to provide a housing for electromechanical vibrator elements having an arrangement for selecting and connecting any one of the elements into a control circuit.

Another object of my invention is to provide 'a housing for a multiplicity of se arate mountings for electromechanical vi rator elements having an arrangement for selecting and connecting any one of the elements into a control circuit.

Still another object of my invention is to provide a structure wherein a multiplicity of electromechanical vibrator elements are maintained at asubstantially uniform temperature and wherein a mechanical arrangement is provided for selecting and. connecting into circuit a selected element.

. A further object. of my invention is to provide a cabinet structure, for housing a multiof electromechanical vibrator elements, with an arrangement for keeping the temperature of the electromechanical vibrator elements which are ositioned in individual holders therein, su stantially uniform 80 a mechanically operable arrangement being provided for connecting a selected one of the electromechanical vibrator elements into circult. I

A still further object of my invention is to provide a cabinet structure, having aplurahty of piezo electric crystal holders there-' in, with heating and heat regulating devices within the cabinet for maintaining the tem perature of the piezo electric crystals substantially uniform and with a circuit making and breakin arrangement operable from the exterior of file cabinet structure for successively connecting into circuit selected ones of the piezoelectric crystals.

According to this invention a cabinet structure having walls made up of layers of heat conductin and heat retaining material is provided orhousin piezo electric cryst each of. which is posilate' completely a plurality of" difierentunit positioned in the heat of the type set forth and described in Letters Patent No. 1,692,063, granted to A. M. Troger on November 20, 1928. A'rotatable contact mechanism is provided within the cabinet structure for engaging contact terminals connected to piezo electric crystal contact plates positioned in the holders. A mechanically actuated mechanism is provided for operating the rotatable contact mechanism "from the exterior of the structure whereby the desired piezo electric crystal may be readily connected into circuit.

A sensitive thermostat isprovided within the structure adjacent to the piezo electric crystal holders for regulating the tempera ture and causing it to remain substantially uniform through the cooperation of a heating unit, the duration of the current flow through which is regulated by the operation of thethermostat. The apparatus within the heat retaining cabinet structure is positioned so that the heated air is caused to circuaround the piezo electric crystal holders. 'The piezo electric elements are thereby maintained at a substantially uniform predetermined temperature. A thermometer, the scale of which is exposed to view from the exterior of the heat retaining structure, is provided to facilitate the manipulation of the system. Each of the piezo electric crystals is calibrated to sustain oscillations ata certain frequency when the piezo electric crystal is at a certain temperature. The frequency of the piezo electric crystal may be varied a certain amount by varying the temperature, for example a certain piezo electric crystal may sustain oscillations of a frequency of 37 50.1 kilocycles at 19 C. and a frequency of 3750.20 kilocycles at 20 C. Each piezo electric crystal is thus pro 'ded with a' frequency temperature chart and by closely observing the reading of 'the thermometer the piezoelectric crystal may be operated directly on the frequency channel assigned for the particular communication. A mechanism for connecting various contacts positioned u on the thermostat, which is preferablyo the mercury expansion type, into circuit so that thecircuits of the heating retaining struc- .ture may be ener 'zed at different temperatures, is provide adjacent to the exterior wall of the heat retaining structure for operation from the exterior thereof.

My invention will be more fully understood from the specification hereinafter following by-reference to the accompanying drawings in which:

Figure 1 illustrates a vertical cross-sectional view through the cabinet heat retaining structure; Fig. 2 illustrates a horizontal cross sectional view through the structure; and Fig. 3 is a detail view of the thermostat and the circuit making switch associated therewith.

In Fi 1 of the drawings, referencenumeral 1 designates a container having an exterior wall 1a of copper, aluminum or similar material. Wall 2 of heat retaining material, such as wood composition having a cellular structure, is positioned within the container 1 against the wall 1a. A metallic plate of copper or other highly conductive material is supported within the container 1 by spacers 4 which are of insulating material, such as hard rubber, phenol condensation products, well annealed porcelain or similar materials.- A circular panel 5 also of insulating material of the nature of hard rubber for making contact with the or phenol condensation products, is supported'adjacent to the plate 3, by spacers 6 which are preferably of machinable in-- sulating material, such as phenol condensation products. Members 7 of insulating material is centrally positioned with respect to the panel 5 and extends upwardly through an openin in the center thereof. A contact lever, of aminated phosphor bronze, brass or similar highly resilient material, is attached to the extremity of member 7 by screws 9. Contact terminals 10 are provided near h the periphery of the panel member 5 as is shown in Fig. 2 of the drawings.

Each of thepiezo electric crystal holders 11 is provided with a top closure member with side walls 11a of insulating material projecting from the base 11b of metallic material, such as copper or brass. A iezo electric element 110 is housed in each 0? the holders. A contact member 11d is rovided in each of the holders for establishing connection with the upper face of the crystal. A spring member 11e of laminated resilient material is also provided within each holder 11 platelld. A contactlng pm 117 of electrica ly conductive material is eld against the side wall of each of the holders by a screw member 11g, which also serves to support the spring lle in position, for engaging the jaws of one of the clamping elements 12, one of which isconnected to each of the terminal contacts 10.

A contacting pin 11h is associated with the base 11?) of each of the holders 11. Clamping springs 13 are fastened to the plate 3 ad- 'acent to each of the holders 11, as shown in ig. 2, for gripping the pins 11h. Each holder 11 is held in position b the clamping action of the members 12 an 13 which also serve to connect the piezo electric crystal 110 into circuit.

A gear mechanism employing beveled gears 14 and 15, supported beneath the plate 3 by members 16,and 17 is provided for actuating the rotatable switching arm 8. The gear 14 is attached .to a metallic member 18 fitted on the rod 7. The gear is attached to the rod 19 which extends out of the container 1. A knob 20 is attached to the end-of the rod 19 for actuating the rotatable arm 8.

The multiple piezo electric crystalholder of this application may be employed in conjunction with systems such as are disclosed in application for Letters Patent, Serial Number 140,376 and Letters Patent No. 1,727,575 dated September 10, 1929, for frequency changing systems and frequency control systems, respectively, of Arthur M. Trogner, in place of the multiple piezo electric crystal holder therein illustrated merely by replacing the knob 20 with a coupling member for the rod 19.

A heating unit, comprising the winding 24 and the winding supporting member 25 is supported by screw and nut member 22 adjacent to the bafile 21. Baille 21 of heat resisting material, such as mica, is supported upon an edge of the plate 3 by the angular member 23 and screw and nut members 29 and 30. A wall 26 of heat resisting material is provided against the inner wall 2 adjacent to the heatin unit to protect the wall 2 from the destructive influence of the heat rays. Connections 27 are provided between the eating unit winding 24 and the terminals 28,

joining an actuating shaft to through which the source of supply is connecte to the heating unit winding. The heated air within the container 1 circulates through the interior of the container in the passage formed between the bafile 21 and the wall 26 and the passage between the bottom of the container and the plate 3 as indicated by the arrows A. The circulating air comes in direct contact with the thermostat 34 which is removably supported adjacent to the plate 3 by the member 35. A switch 36, operated by the knurled knob-37, is supported upon a panel member 39 exteriorly of the-container 1. The bulb portion of the thermometer 40 is positioned upon the plate 3. The constricted portion of the thermometer 40 projects outwardly of the container 1 and is held against the panel 39 by the bracket 41. A transparent panel 42 is provided in an opening in the panel 39 so that the indications of the thermometer may be viewed. A ring shaped member 31 of conducting material is 1,sea,aaa

hold the spacers 4 and spacers 43 to the bottom of the container 1. Connections between the ring 31 and the plate 3 which is of conducting material, are led to the exterior of the container 1 through bushings 46 and 47 which are of insulating material.

The front wall 1?; of the container 1 is removable to provide access to the interior of the container. In some cases it is more desirable to have the top wall removable.

This, however, is optional and depends upon the arrangement in the signalin system.

In Fig. 3 a detail view of the t ermostat 34 and the contacting arrangement 36 whichis actuated by the knob 37 is shown. The thermostat 34 which is of the mercury expansion type is provided with a plurality of electrodes 49, 50,51, 52 and 53. More electrodes may be provided if it is found desirable.

The electrode 49 is connected to a terminal of the relay 240. The rotatable contacting member'48a associated with the knob 37 is connected to a terminal of the source 24d, the other terminal of which is connected to the "relay 240. A. second relay 24a is connected to the source of current supply 241) and then to the contactin arrangement actuated by the windin 0% relay 240. The relay'24a is associated with the circuit of the source of current supply 24c and the heating unit 24, which is positioned in container 1. Electrodes 50, 51, 52 and 53- are connected to the stationary contacts a, 51a, 52a and 53a, res ectively.

In operation t e knob 37 is rotated until the contacting arm 48a is in electrical contact with one of the stationary contacts 50a, 51a, 52a or 53a. The selection of the stationary contact isdetermined b the temperature at which it is desired to have the temperature control system operate. The thermostat34 may be so calibrated that at 20 C. the circuit between electrodes 49 and 50 is established, at 30 C. the circuit between electrodes 49 and 51 is established, 40 C. the circuit between 49 and 52 is established and at 50 C. thecircuit between 49 and 53 is established. The temperature within the container 1. maybe re ated at any predetermined temperature or which the thermostat is calibrated by selecting the proper elec- 52 and 53 may be so arranged trode of the thermostat with the switching mechanism 36, 37. The electrodes 49, 50, 51,

that an electrical circuit between electrodes 49 and 50 is completed at temperature of 48 C. and the circuit between the electrode 49 and each of the successive electrodes 51, 52, and 53 is completed at 49 C., 50 C., 51 (1., and 52 C.,

respectively. In practice piezo electric crystals operating at frequencies around 4000 "kilocycles are usually ground to a thickness such that their frequencies are within 500 cycles of the desired fre uenc and it is therefore highly desirable to e ab e to either raise or lower the temperature within the piezo electric crystal housing to be able to adjust the frequency of the piezo electric crystal used, to the desired frequency.

While I have described my invention in one of its preferred embodiments, I desire that it be understood that other modifications thereof may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a system of the class described the combination of a container having walls of heat retaining material, a plurality of piezo electric elements located in a substantially circular 'row within said container, means disposed concentrically within said row of piezoelectric elements within said container for connecting selected ones of said piezo electric elements mto circuit, means extending beneath said row of elements for actuating said first named means, said second mentioned means being controlled from the exterior of said container, a heating unit positioned within said container, a thermostat positioned in said container, means whereby said thermostat controls the temperature within said container and a bafile member disposed adjacent said heating unit for directing the circulation of heated ases.

2. In a system oftIie class described the combination of a container having walls of 3. In asystem of the class described the "combination of a container having walls of heat retaining material, an electromechanical vibrator positioned within said container, a'plate of heat conducting materlal for supbaflie adjacent to saidheating unit,

porting said electromechanical vibrator away from the walls of said container, said plate fitting closeto a pair of opposite walls of said container, a heating unit for heating the gase- 5 ous medium within said container and causing said medium to circulate, means positioned adjacent to said heating unit for causing the circulating medium to circulate beneath said plate of heat conducting material, and a thermostat positioned within said container, said thermostat being arranged to control the temperature within said container.

4. In a system of the class described the combination of a container having walls of heat retaining material, a plate of heat conducting material for supporting said electromechanical vibrator away from the walls of said container, a heating unit positioned in said container for heating the gaseous medium in said container to a predetermined temperature and causing said gaseous medium to circulate about said electromechanical vibrator, and a thermostat positioned in said container, said thermostat having a plurality of contacts, a switching mechanism, connections between said switching mechanism and each of said contacts, said switching mechanismbeing operable to connect selected ones of said contacts associated with said thermostat whereby the temperature within said container may be maintained at any one of a plurality of temperatures.

-5. In a system of the class described the combination of a container, a base member mounted therein, a plurality of electromechanical vibrators carried by said base memher within said container, an insulated platform extending from said base, contacts individual to each of said vibrators disposed in a circular row on said platform, a rotatable switch passing through said platform and movable to each of said contacts, a heating.

unit positioned in said container, mechanical means for actuating said rotatable switch;- from the exterior of said container for making andbreaking the connections to said electromechanical vibrator, arthermostat within' said container, a switching mechanism associated with said thermostat for controlling the efiective operating temperature thereof, and battle members positioned adjacent said heating unit and said thermostat for directmg the circulation of heated gases past said thermostat.

- 6. In a system of the class described the combination of a container having'walls of heat retaining material, a plurality of electromechanical vibrators positioned within said container, 2; heat conduct-ing plate for away from the bottom of said container, a bafiie positioned upon said plate, a heating unit positioned along one side of said baiile, a thermostat positioned upon said plate, a thermometer positioned within said container,

supporting said electromechanical vibrators and a rotatable switching mechanism, said electromechanical vibrators being connected to contacts of said rotatable switching mechanism.

'Z. In a system of the class described the combination of a container having walls of heat retaining material, a plurality of electromechanical vibrators positioned in said container, a plate member of heat conducting material for supporting said electrbmechanical vibrators, a rotatable switching mechanism, a heating unit, apanel of insulating material, contacts positioned upori said panel, connections between said contacts and said electromechanical. vibrators, said rotatable switching mechanism being adapted for engaging said contacts, and means for actuating said rotatable switching mechanism from the exterior of said container.

8. In a temperature control system for piezo electric elements, a heat insulated cabinet, a metalplate mounted in said cabinet adjacent one side thereof and substantially parallel thereto, a multiplicity of piezo electric elements mounted on said metal plate, means within said cabinet for selectively connecting said piezo electric elements into circuit,'a bafiie plate mounted adjacent a side of said-cabinet other than the side adjacent said metal plate, aheating unit mounted between said battle plate and the adjacent side of said cabinet,'a thermostat mounted between said metal plateand the sid' of said cabinet adjacent thereto, and means whereby said thermostat controls the operation of said heating unit.

9. In a temperature control svstem for piezo electric elements, a heat insulated cabinet, a metal plate mounted in said cabinet adjacent one side thereof and substantially parallel thereto, a multiplicity of piezo elec-' tric elements mounted onsaid plate, means ,within said cabinet for selectively connecting said piezo electric elements into circuit, baiiie members adjacent the sides of said cabinet no for defining a gas circulation path, a heating unit mounted in said gas circulation path, a thermostat mounted in said gas circulation path adjacent said piezo electric element, and

means whereby said thermostat controls the operation of said heating unit.

LOUIS A. GEBHARD. 

